Chemical Composition of Ash in Ulug-Khem Coal

The chemical composition and properties of coal ash from the Kaa-Khem (GZh), Mezhegey (Zh), and Elegest (Zh) fields in the Ulug-Khem Basin are compared in order to develop recommendations for the use of such coal. Elemental analysis, Fourier transform infrared (FTIR) spectroscopy, and X-ray fluorescent spectroscopy are used to study the organic and mineral components of the coal and to determine the main ash components (SiO2, Al2O3, Fe2O3, CaO, etc.). In accordance with State Standard GOST 11022–95, the ash content of the coal is determined at 815 ± 10°C. The fusibility characteristics (softening point and melting point), the slag viscosity, and the slagging and fouling are calculated. It is found that the ash from the Kaa-Khem coal (39% SiO2, 14% Al2O3, 21% Fe2O3, and 12% CaO) is very thermostable (tso = 1154.6°C). The ash from the Mezhegey coal (10% SiO2, 8% Al2O3, 36% Fe2O3, and 24% CaO) is of elevated basicity (Ib = 3.83), with a low melting point (1105.2°C). The ash from the Elegest coal (32% SiO2, 19% Al2O3, 23% Fe2O3, and 14% CaO) has a balanced composition, with moderate slag viscosity. Thus, the samples with high melting point (Kaa-Khem and Elegest coal) have little risk of slagging, whereas the Mezhegey coal requires additional measures to decrease the fouling (Rf = 3.28). The results confirm that Tuvinian coal is promising for practical use, if the specifics of the ash are taken into account.